Now we can call it the Yahoo effect for the company’s chief executive Scott Thompson. Confronted with the fact that it was unlikely that he earned a degree in computer science — since his college didn’t offer such a degree until four years after he graduated — Thompson went all last cookie. It was, he said, an”inadvertent error.”

Actually, it wasn’t. He didn’t accidentally check the wrong box on a form, or suffer amnesia. At some point, he lied about his degree. And, given subsequent opportunities to correct that, he didn’t.

And now it has taken on a life of its own. Worst of all, the claim that he has the degree appeared on a legal document filed with the Securities and Exchange Commission. A major Yahoo shareholder — who has motives of his own — is demanding that he resign.

Thompson defenders are working the angles. These days, they say, everyone pads their resume a little. This was just an exaggeration. And besides, did the troubled Yahoo firm hire Thompson four months ago because of his academic record or because he’s been successful elsewhere and has a plan to turn the company around?

Here’s what I would say. It isn’t an exaggeration. It’s a lie. And his previous success at other companies is proof that he didn’t have to juice up his resume to be successful. Look, we know that people lie sometimes. It happens to the best of us. That’s not what defines our character.

It’s what you do when you afterwards, after a little thought.

You admit it, you apologize, and you accept the consequences. Your move, Scott.